This application is for completion of the project started two years ago under the title METHADONE TEMPORARY SUPPORT USING LAAM AND NALTREXONE. We are testing the efficacy of short-term substitution of a surrogate opiate (LAAM) for heroin, followed by naltrexone to aid in maintaining abstinence. In the first cohort, 179 patients were admitted to treatment; we expect about the same number in the second cohort. Follow-up will be at one and two years following termination. In the course of this study various ancillary data are being obtained, such as detailed information about LAAM safety and toxicity, experience with rapid induction onto LAAM, experience with naloxone testing for heroin dependence, comparison of fast and slow withdrawal from LAAM, experience with a new method of monitoring the validity of urine samples, and experience in developing tools for effective education of patients about naltrexone.